ALPHP004 disclosed a semiconductor MOSFET device, with associated manufacturing method, having a gate trench extending through its source and body into its drain, a gate disposed in the gate trench, a source body contact trench having a trench wall and an anti-punch through implant that is disposed along the trench wall. Corresponding to the existence of gate trench and source body contact trench, two contact etchings may be required for device manufacturing.
ALPHP005 disclosed a semiconductor MOSFET device, with associated manufacturing method, formed on a semiconductor substrate. The device comprises a drain, an epitaxial layer overlaying the drain, and an active region. The active region comprises, inter alia, a gate trench extending into the epitaxial layer and an active region contact trench extending through the MOSFET source and at least part of the MOSFET body into the drain. As illustrated in FIG. 4O (first contact etch) and FIG. 4R (second contact etch) with accompanying descriptive text in the ALPHP005 specification, two contact etchings are required for device manufacturing.
ALPHP008 disclosed a MOS device with integrated Schottky barrier controlling layer and ALPHP009 disclosed a MOS device with integrated low injection diode.
Thus, while the structure of a MOSFET device integrated with a Schottky Diode (MOSFET/SKY) is known in the art, the present invention is directed to its manufacturing method that is simplified and that also produces devices with more consistent device performance. More specifically, to those skilled in the art, it is not uncommon to see substantial trench geometrical tolerances around +/−10% resulting from contact etching. Multiple contact etching steps, in addition to complicating the manufacturing process, will compound thus aggravating the already substantial trench geometrical tolerances from a single contact etching. Therefore, the present invention deals with making an MOSFET/SKY with simplified one-time top-contact trench etching.